Some pharmaceuticals are more stable over time if certain volatile components are removed. The process for removing the volatile components is called lyophilization. Solvents, including water, are examples of the components to be removed. Typically, lyophilization is carried out at elevated temperatures in a lyophilization chamber or oven. Usually a vacuum is created to facilitate volatilization. This permits removal of the solvents by sublimation. The pharmaceutical to be lyophilized is commonly in the form of a slurry. The lyophilized pharmaceutical is usually reduced to a solid, typically in a powdered or a crystallized form.
Lyophilized pharmaceuticals are widely used in the clinical setting because of their long shelf life, ease of storage and transport, and their reliable purity. The shelf life is long because the pharmaceutical is in a dry, inert form. Storage and transport are relatively easy because the powder or crystal is light-weight compared to its liquid form. Also, there are usually not special temperature requirements such as refrigeration. Sealed in a container, the lyophilized pharmaceutical does not require delicate handling, but is rather durable.
The purity of the substance is reliable if the container is properly sealed because contamination is prevented. Contamination can include introduction of unwanted microorganisms, atmospheric water vapor, gases (including oxygen), and particulate matter. The long shelf life and reliable purity of lyophilized substances are dependent in part on their handling after lyophilization and on the integrity of the sealed container. The introduction of contaminants can occur after lyophilization but before sealing the container, or after sealing if the seal is inadequate or violated.
In some cases lyophilized pharmaceuticals are distributed in pharmaceutical cartridges of the type including a barrel, a piston at one end and a piercible septum held in place over the mouth at the other end of the cartridge by a metal band or cap. To prepare the cartridge for use, a double ended needle cannula is mounted to the cartridge. The cannula pierces the septum and introduces a reconstituting agent, such as a sterile saline solution, into the cartridge by manipulation of the piston in a conventional manner. Sometimes the lyophilized pharmaceutical is distributed in a vial or ampule instead of the cartridge assembly. The vial or ampule may be sealed by means of a top that is removable or piercible. The pharmaceutical may be reconstituted either by removing the top and adding the reconstituting agent or by inserting a double ended needle cannula through the piercible top and introducing the reconstituting agent through the cannula.
Once the pharmaceutical has been lyophilized, the mouth of the cartridge is sealed, typically with a septum held in place by a band or a cap. Although this could occur outside the lyophilization chamber, there are recognized advantages to sealing the lyophilized pharmaceutical-containing cartridge within the chamber. One advantage is that a clean, dry environment can exist in the chamber after the lyophilization process and before the chamber is opened. Sealing the container before removal from the chamber could reduce the risks of contamination and spill of the unsealed dried product. The result is simplified production of contained, sealed lyophilized substances.
One way to seal the cartridge while still in the oven would be to mount a sealing cap at the mouth of the cartridge. The cap would be configured to provide relatively unhindered fluid access between the lyophilization chamber and the interior of the cartridge through the mouth while the cap is in a first position. After lyophilization, it was conceived that the cap would be secured onto the cartridge in a second position causing the septum to cover the mouth. However, an acceptable configuration for the sealing cap and method for accomplishing this was not available prior to the present invention.
An attempt to accomplish sealing the container while within the lyophilization chamber is known in the prior art. A one piece polycarbonate plastic cap with two septums was used. The cap was to occupy a first position during lyophilization and a second position after lyophilization while still in the chamber. The cap was forced into position after lyophilization, but because the plastic deformed during the lyophilization process, the container leaked. The present invention solves some of the problems known in the prior art.